Adolescent sexual risk taking behavior has become a major public health concern in the United States, and it presents an urgent need for researchers to understand the precursors of sexual risk and the developmental pathways through which sexual risk taking develops. Contributing to the complexity of preventing sexual risk behavior is substantial research documenting the co-occurrence of adolescent sexual risk taking and high rates of delinquency and substance use. In fact, sexual risk taking is often examined from the broader perspective of problem behavior syndrome, which is based on the idea that there are common causes and influences underlying all three problem behaviors. However, recent research suggests that strong associations among sexual risk, substance use, and delinquency may not occur for all adolescents, which raises questions about the precise nature of the relationship between sexual risk and other problem behaviors as well as their developmental antecedents. This study plan provides the opportunity to disentangle the development and co-occurrence of these youth risk trajectories in order to understand the diverse developmental pathways of adolescent sexual risk-taking over time. Data for this proposed study come from the child and young adult datasets from the National Longitudinal Survey of Youth (NLSY79), an ongoing large-scale study that follows both the original 1979 sample and their children with extensive assessments. This study will use General Growth Mixture Modeling methodology to follow 2,788 children of the original sample over a period of ten years in order to address three specific aims: (1) to describe the diversity of adolescent patterns of risk within sexual risk and other problem behaviors using growth curve analytic techniques; (2) to identify how differing levels of risk across sexual risk forecast adolescents' engagement in multiple problem behaviors; and (3) to elucidate how childhood processes of risk and protection may influence youth membership in sexual risk trajectory groups. An overarching aim of this study is to begin to capture the complexity of the developmental course of sexual risk behavior with co-occurring risk behavior trajectories and to reveal how processes of risk and protection forecast the unfolding of these health-risk behaviors. Such increased understanding of youth developmental problem behavior trajectories can inform specific intervention efforts designed to prevent and mitigate the development of distinct patterns of sexual risk behaviors over the course of adolescence. Progress in illuminating these protective processes can ultimately enhance the specialization of intervention efforts to an increasingly diverse population of adolescents and support adolescent health and well-being. [unreadable] [unreadable] [unreadable]